Process for isomerizing ethylenically unsaturated compound possessing cycloaliphatic nucleus



United States Patent 3,375,287 PROCESS FOR ISOMERIZING ETI-IYLENICALLYUNSATURATED COMPOUND POSSESSIN G CY- CLOALIPHATIC NUCLEUS Samuel W.Tinsley, Edward A. Rick, and James E. Mc-

Keon, Charleston, W. Va., assignors to Union Carbide Corporation, acorporation of New York No Drawing. Continuation of application Ser. No.396,416, Sept. 14, 1964. This application July 21, 1967, Ser. No.655,239

23 Claims. (Cl. 260-4566) ABSTRACT OF THE DISCLOSURE This inventionrelates to the isomerization of an ethylenically unsaturated compoundwhich contains a cycloaliphatic nucleus.

This application is a continuation of Ser. No. 396,416

,filed Sept. 14, 1964, now abandoned, which in turn was acontinuation-in-part of Ser. No. 134,846, filed Aug. 30, 1961, nowabandoned.

Various processes are available for isomerizing olefins; however, suchprocesses are, in general, limited in scope and in addition, suffer fromone or more limitations such as unfavorable equilibrium conditions,excessive cracking of the olefinic reagent, undesirable polymerizationof the olefinic reagent, and the like.

In a broad aspect, the present invention is directed to a process forisomerizing an isomerizable ethylenically unsaturated compound having acycloaliphatic nucleus in the presence of a catalyst, said catalystbeing described hereinafter in detail. It becomes apparent, therefore,that the practice of the novel process affords a convenient means forobtaining various ethylenically unsaturated monomers which are notreadily commercially available or which can only be prepared by moreexpensive and timeconsuming prior art routes. For instance, theoperative examples contained in this specification disclose theisomerization of non-conjugated diolefinic compounds such as4-vinylcyclohexene and 1,5-cyclooctadiene to conjugated diolefinicproducts namely, 1-ethyl-1,3-cyclohexadiene and 1,3-cyclooctadiene,respectively. The isomerized products which are obtained in accordancewith the practice of the novel process possess, of course, utilityasreagents in the preparation of alcohols, ketones, acids, amines,epoxides, and various other derivatives. In addition, the isomerizedproducts can be employed as the diene or, in some instances, thedienophile in the wellknown Diels-Alder reaction, or as a monomericsource in the preparation of useful polymers. The literature veryadequately describes numerous routes which utilize the isomerizedproducts.

The ethylenically unsaturated compounds which can be employed in theprocess of this invention typically are composed solely of carbon andhydrogen, a cycloaliphatic nucleus having up to 16 carbon atoms in saidnucleus, preferably up to 12 carbon atoms in said nucleus, and at leastone migratable ethylenic bond. By the term migratable ethylenic bond, asused herein including the appended claims, is meant an ethylenic bond,i.e.

which is bonded in the compound to a carbon atom in the alpha (or)position to the ethylenic bond, which alpha carbon atom bears at leastone hydrogen atom. The ethylenic unsaturated compounds most favorablyem- Patented Mar. 26, 1968 ployed herein contain at least one migratableethylenic bond which is an isomerizable ethylenic bond, i.e.

By the term isomerizable ethylenic bond, as used herein including theappended claims, is meant an ethylenic bond, i.e., C=C which is notpresent in its most thermodynamically favored position in theethylenically unsaturated molecule. Similarly, compounds containing oneor more migratable ethylenic bonds (or the more specific isomerizableethylenic bonds) are referred to herein, including the appended claims,as isomerizable compounds. The ethylenically unsaturated compounds whichare contemplated include, for instance, .the isomerizable cycloolefinichydrocarbons which contain 2 to 3 ethylenic bonds such as theisomerizable cyclodiolefins and the isomerizable cyclotriolefins, e.g.,1,4-cyclohexadiene, 1,4-cycloheptadiene, 1,5-cyclooctadiene,1,4,-cyclooctadiene, the isomerizable cyclononadienes, the isomerizablecyclodecadienes, the isomerizable cyclododecadienes, the isomerizablecyclohexadecadienes, 1,3,6-cyclooctatriene, the isomerizablecyclodecatrienes, the isomerizable cyclododecatrienes, the isomerizablecyclohexadecatrienes, and the like; the isomerizable alkyl substitutedcycloolefinic hydrocarbons which contain from 1 to 3 ethylenic bonds,preferably the isomerizable lower alkyl substituted cycloolefinichydrocarbons, e.g., the isomerizable alkylcyclopentenes,3-methylcyclopentene, 4-methylcyclopentene, 3,4-dimethylcyclopentene,4-ethylcyclopentcue, the isomerizable alkylcyclohexenes,4-methylcyclohexene, 4-n-butylcyclohexene, the isomerizablealkylcycloheptenes, 3-isopropylcycloheptene, the isomerizablealkylcyclooctenes, S-methylcyclooctene, the isomerizabledimethylcyclooctenes, the isomerizable alkylcyclodecenes,3-ethylcyclodecene, the isomerizable alkylcyclododecenes, theisomerizable alkylcyclohexadienes, 1-propyl-1,4-cyclohexadiene, theisomerizable alkylcycloheptadienes, the isomerizablealkylcyclooctadienes, the methyl-1,5-cyclooctadienes, theclimethyl-1,5-cyclooctadienes, the isomerizable alkylcyclodecadienes,the trimethyl-1,5-cyclododecadienes, the isomerizablealkylcyclooctatrienes, the methylcyclooctatrienes, the isomerizablealkylcyclodecatrienes, the isomerizable methylcyclodecatrienes, theisomerizable alkylcyclododecatrienes, the trimethyl-1,5,9-cyclododecatrienes, and the like; the isomerizable ,vinyl substitutedcycloolefinic hydrocarbons which contain'from 1 to 3 ethylenic bonds,e.g., 4-vinylcyclohexene, the methyl-4-vinylcyclohexenes, 4isopropenyl-cyclohexene, and the like; the isomerizable vinylsubstituted cycloalkanes, e.g. vinylcyclopentane, vinylcyclohexane,vinylcycloheptane, vinylcyclooctane, 2-methylenebicyclo[2.2. 1]-heptane, 2-methylbicyclo[2.2.l]hept-2-ene, andthe like.

To illustrate this, separate samples of 2-methylenebicyclo[2.2.l]heptaneand 2-methylbicyclo[2.2.1]hept-2-ene were each sealed in glass tubeswith bis-benzonitrile palladium II) chloride and heated for varyingperiods of time. The reaction products weretanalyzed by vapor phasechromatography. The following tables show the results oftheseexperiments:

Milligrams Mole percent Mole percent Exp. P1101 24: ON 'Iem TuneZ-methylbi- Z-methylene- N0. employed as 0.) (hrs) cyc1o[2.2.1]-blcyclo[2.2.1]-

catalyst -hept-2-ene heptane Milligrams Mole percent Mole percent Exp.PdCl2.2CN Temp. Time 2-methylbi- Z-methylene- No. employed as C.) (hrs)cyclo[2.2.l]- bicyclo[2.2.1]-

catalyst hept-Z-ene heptane The above experiments illustrate that anequilibrium in the isomerization reaction can exist tending to favor themore stable isomeric form. However, there are instances whereisomerization results in essentially complete conversion to the morestable isomeric form-at least in such cases the relatively unstableisomeric form is not detectable. Either one of the isomeric formsresulting in the equilibrium mixture may be withdrawn from the reactionequilibrium products and so long as the products are maintained in thepresence of isomerization catalyst, more product is produced. Thus, ifin the above case, Z-methylbicyclo[2.2.1]hept-2-ene is isolated from thereaction mixture, e.g., by distillation, equilibrium will be continuallyreestablis-hed upon removal of the isomeric specie and more2-methylbicyclo[2.2.1]hept-2-ene will be produced. As a result, yieldsof this specie far in excess of the 12 to 13 mole percent indicatedabove in the equilibrium mixture is obtainable from a given amount ofstarting material. In this manner, it is possible to obtain appreciablehigh yields of any one of the isomeric products obtained from theisomerization process of this invention. For example, in theisomerization indicated in Table II above, if the lower boiling2-methylbicyclo[2.2.1]hept-2-ene is distilled and the distilled productis contacted with additional catalyst, it can be isomerized to form anequilibrium mixture thus producing substantially greater yields of themore stable isomeric form, to wit, Z-methylenebicyclo[2.2.1]heptane.

The process of this invention favors the isomerization of anethylenically unsaturated compound containing isomerizable ethylenicbonds. This is evident from analysis of the isomerization reactionproducts which typically contain an equilibrium mixture of the favoredand predominant product as well as some of the less favored isomericstarting material. By upsetting the equilibrium of the isomerizationreaction, i.e., by withdrawing some or all of the more thermodynamicallyfavored product, greater yield of such product is obtainable.

In the isomeric conversion of a more thermodynamically favored isomerizable product containing migratable ethylenic bonds, utilizing the processconditions taught herein, there is formed also an equilibrium mixture ofthe isomeric mixture, Le, a mixture of the thermodynamically favoredisomer and the less thermodynamically favored isomer(s). By withdrawingthe less favored isomer from the mixture, by, e.g., distillation,equilibrium is reestablished and more of the less favored isomer isproduced. Thus high yields of such product are attainable.

The catalysts which are contemplated are those transi tion metal ionsand atoms which are capable of forming d.sp. (square planar) hybridorbitals. By transition metals as used herein is meant those elements ofthe periodic system which are characterized by atoms in which an innerd. level of electrons is present but not filled to capacity. With theexception of the nickel series (Ni, Pd, and Pt) and the cobalt series(Co, Rb, and Ir), these transition metal catalysts can possess a neutralcharge or a positive charge, and they include those elements which havean atomic number ranging from 22 i028, inclusive, from 40 to- 46,inclusive, and from 72 to 78, inclusive. Alternatively, the transitionmetals which are contemplated include the Group IVB, VB, VIB, VIIB, andVIII elements of the periodic chart. Specifically, these transi-Per-iodieChart of the Elements. by the Fisher Scientific Company, NewYork, copyright 1957.

and Hf The preferred metals are those from the Group VIII nickel series(Ni, Pd, and Pt), the Group VIII cobalt series (Co, Rh, and Ir), and theGroup VIII iron series (Fe, Ru, and Os). It is pointed out that theessential catalytic entity is the transition metal in one of theoxidation states illustrated supra which thus is capable of formingd.sp. hybrid orbitals. A wide variety of compounds which contain thetransition metal in its proper oxidation state can be employed tofurnish the active catalyst species providing said compounds form ahomogeneous phase with the reaction medium under the operativeconditions of the process. A co-solvent inert with respect to theisomerizable reagent, may be employed to bring about the requiredhomogeneity. The moieties which can be bonded to the transition metal inorder to form a neutral compound (which provides the catalytic specieswhen added to the reaction medium) can be selected from a large group ofions and neutral ligands. Illustrative of the charged moieties include,for instance, the halide ions; the hydride ion; the carbanions, e.g.,alkyl anion, phenyl anion, and the like; the cyclopentadienylide anions;the mallyl groupings; the enolates such as the enolates ofbeta-dicarbonyl compounds, e.g., acetylacetonates and the like; theanions of acidic oxides of carbon (carboxylate, carbonate, etc.),nitrogen (nitrate, nitrite, etc.), phosphorus (phosphate, phosphite,etc.), bismuth (bismuthate, etc.), aluminum (aluminate, etc.), silicon(silicate, etc.), sulfur (sulfate, sulfite, etc.), molybdenum(molydates, etc.), and the like, in which one valence of the centralatom of the acidic oxide may be attached to carbon, and/or in which oneof the oxygen atoms may be attached to carbon; and the like; protons andother positive ions, e.g., Na+, K' Ca++, and the like. In addition,exemplary neutral moieties which are contemplated include, among others,the olefins; the acetylenes; the acetylenic olefins; the aromaticcompounds, e.g., benzene, diphenyl, and the like; carbon monoxide;nitric oxide; the basic nitrogen compounds, e.g., ammonia, the anilinespyridines, dipyridines, amines, imines, amides, imides, ureas, oximes,nitriles, hydroxamie acids, amino acids, and the like; the organicethers, e.g., dimethyl ether of diethylene glycol, dioxane,tetrahydrofuran, furan, diallyl ether, and the like; the phosphines,e.g., phosphine, the alkylphosphines, the arylphosphines, thealkarylphosphines, and the like, and analogous compounds of antimony,arsenic, and bismuth; the phosphites, e.g., the alkyl, aryl-,alkarylphosphites, and the like; the phosphine oxides; the phosphoroushalides; the phosphorous oxyhalides; the sulfides, e.g., the

alkyl-, aryl-, alkarylsulfides, and the like; the cyclic sulfides; theunsaturated sulfides, the sulfoxides, e.g., aryl-, alkyl-,alkarylsulfoxides, and the like.

Specific compounds which can be employed to provide the catalyst speciesinclude, for example, Fe (CO) Fe(NO) (CH CN) C H Fe(CO) C H Co(CO) (3 )22, s rJz s s s s e, 5 5)2 C H IrC H K PtCl Mu(NO) (CO), C H Mn(CO) C HMn(C H (CO) ReCl(C CH) dimethylpiperazine palladous chloride,cyclopropane platinous chloride, indene chromium(0) tricarbonyl,fiuorene chromium(0) tricarbonyl, rr-allyl-vr-cyclopentadienylpalladium,and the like.

The preparation of typical compounds capable of supplying the catalystspecies is documented in the literature.

' The catalysts are employed in catalytically significant quantities. Ingeneral, a catalyst concentration in the range of from about 0.001, andlower, to about 10, and higher, weight percent, based on the weight ofthe ethylenic reagent, is suitable. A catalyst concentration in therange of from about 0.005 to about 8.0 weight percent is preferred. Acatalyst concentration in the range of from about 0.01 to about 5 weightpercent is highly preferred. For optimum results, the particularcatalyst employed, the nature of the ethylenic reagent, the operativeconditions under which the isomerization reaction is conducted, andother factors will largely determine the desired catalyst concentration.It is highly desirable that the catalyst be soluble in or miscible withthe ethylenic reagent.

The isomerization reaction can be conducted over a wide temperaturerange and generally at an elevated temperature. Depending upon variousfactors such as the nature of the ethylenic reagent employed, theparticular catalyst employed, the concentration of the catalyst, and thelike, the reaction temperature can be as low as 0 C., and lower, and ashigh as 350 C., and higher. A suitable temperature range is from about25 C. to about 225 C. A reaction temperature in the range of from about40 C. to about 200 C. is preferred.

The isomerization reaction preferably occurs in the liquid phase, and tothis extent sufficient pressure is employed to maintain an essentiallyliquid reaction'mixture regardless whether or not an inertnormally-liquid organic vehicle is employed.

In general, the reaction time will vary depending on the operativetemperature, the nature of the ethylenic reagent employed, theparticular catalyst and the concentration employed, and other factors.In view of the illustrative variable noted above, the reaction isconducted for a period of time sufiicient to produce a shift in theposition of the double bond of the isomerizable reagent. It has beenobserved that desirable results can be obtained by conducting thereaction for a period of time ranging from several minutes to severalhours, or longer. In general, a reaction time of from about 0.5 hour,and lower, to about 24 hours, and higher, is suitable.

The process of the invention can be executed in a batch,semi-continuous, or continuous fashion. The reaction vessel can be aglass vessel, steel autoclave, elongated metallic tube, or otherequipment and material employed in the isomerization Iart provided thatthe catalyst-containing compound is not sensitive to this material ofconstruction. The order of addition of catalyst and ethylenic reagentdoes not appear to be critical. A suitable procedure is to add thecatalyst to the reaction zone containing the ethylenic reagent. Ifdesired, the catalyst'can be in solution or suspension (e.g., in aninert normally-liquid organic vehicle). Incremental addition of catalystto the reaction zone can be employed. If desired, the above procedurecan be reversed, that is, the ethylenic reagent can be added to thereaction zone containing the catalyst (or a catalyst solution orsuspension).

Unreacted ethylenic reagent and isomerized product can be recovered fromthe resulting reaction product mixture by conventional techniques suchas by distilling said reaction product under reduced pressure.

The following examples are illustrative:

EXAMPLE 1 Vinylcyclohexene (1007 grams) and cobaltocene (50 grams) werecharged to a three-liter stainless steel bomb and were maintained at 185C. for fifteen hours. The resulting reaction product mixture was flashdistilled and Organo-Metallic Compounds, by G. E. Coates, John Wiley andSons, Inc., New York (1956) Chemical Reviews, volume 55, pages 551-594,The Williams and Wilkins Company. Baltn more (1955) McClellan et al., J.Am. Chem. Soc., S3, 1601 (1961).

then carefully fractionated. There was obtained 232 grams ofl-ethyl-1,3-cyclohexadiene.

EXAMPLE 2 Nickelocene (1.65 grams) and 4-vinylcyclohexene (33 grams)were charged to a heavy-walled glass tube. The tube was sealed and thenmaintained at 180 C. for 18 hours. Flash distillation of the resultingreaction product mixture gave 19 grams of distillate. Vapor phasechromatography revealed that this was a mixture composed of4-vinylcyclohexene, 1-ethyl-l,3-cyclohexadiene, and other-components.

EXAMPLE 3 To a 500 milliliter bomb, there were charged 167 granis of4-vinylcyclohexene and 10 grams of cyclopentadienyl cobalt1-benzoylcyclopentadiene-1,3. The bomb then was heated to about 180 C.for 15 hours. Flash distillation of the resulting reaction productmixture yielded a complex mixture which contained 60 weight percentl-ethyl- 1,3 cyclohexadiene.

EXAMPLE 4 Nickelocene (1.75 grams) and 1,5-cyclooctadiene (35 grams)were charged to a heavy-walled glass tube. The tube was sealed and thenmaintained at 180 C. for eighteen hours. Flash distillation of theresulting reaction product mixture gave 23 grams of distillate. Vaporphase chromatography of a hearts cut (17 gms.; B.P. 210 C.; N 30/d1.4850) revealed that it was a mixture containing weight percent1,3-cyclooctadiene. Only a faint trace of 1,5-cyclooctadiene could bedetected. The infrared spectrum of the crude reaction product was nearlyidentical to that of authentic 1,3-cyclooctadiene; B.P. 54 C./36 mm. ofHg, N 30/d 1.4884.

The same isomerization reaction conducted at C. for eighteen hoursafforded 23 grams of distillate containing 18 weight percent1,3-cyclo0ctadiene and 60 weight percent 1,5-cyclooctadiene.

EXAMPLE 5 The PdCl -2(C H CN) (1.75 grams) and 1,5-cyclooctadiene (35grams) were charged to a heavy-walled glass tube. The tube was sealedand then maintained at 180 C. for 18 hours. At the end of this period oftime the inside of the tube was coated with a metallic palladium mirror.Flash distillation of the resulting reaction product mixture yielded 14grams of distillate. Vapor phase chromatography .revealed that thedistillate was 91.6 weight percent 1,3-cyclooctadiene,

EXAMPLE 6 EXAMPLE 7 The PdCl -2(C H CN) (15 grams) and1,5-cyclooctadiene (500 grams) were placed in. a 500 ml. flask and wererefluxed for 4 hours under a nitrogen atmosphere. Vapor phasechromatography revealed that the resulting reaction product mixture wascomposed of 80 weight percent 1,3-cyclooctadiene, 8 weight percent1,5-cyclooctadiene, and 12 weight percent 1,4-cyclooctadiene.

EXAMPLE 8 To a heavy-walled glass tube, there were charged 35 grams of1,5-cyclooctadiene and 1.75 grams of 1,5-cyclo- 7 octadiene palladium(II) chloride. The tube was sealed and then maintained at 180 C. for 18hours. Flash distillation of the resulting reaction product mixture gavegrams of distillate. Vapor phase chromatography revealed that thedistillate contained 92.2 weight percent 1,3-cyclooctadiene.

EXAMPLE 9 To a heavy-walled glass tube, there were charged 35 grams of1,5-cyclooctadiene and 1.75 grams of bis(cyclopentadienyl) titaniumdicarbonyl. The tube was sealed and then maintained at 180 C. for 18hours. Flash distillation of the resulting reaction product mixture gave23 grams of distillate. Vapor phase chromatography revealed that thedistillate contained 51.6 weight percent 1,5-cyclooctadiene, 18.5 weightpercent 1,3-cyclooctadiene, and weight percent 1,4-cyclooctadiene.

EXAMPLE 10 To a heavy-walled glass tube, there were charged grams of1,5-cyclooctadiene and 1.75 grams of cyclopentadienyl cobalt 1benzoylcyclopentadiene-l,3. The tube was sealed and then maintained at atemperature of 180 C. for 18 hours. Flash distillation of the resultingreaction product mixture gave 28 grams of distillate. Vapor phasechromatography revealed that the distillate contained 1,3-cyclooctadiene.

EXAMPLE 1 1 The 1,5-cyclooctadiene (4 grams) and iron pentacarbonyl (0.2ml.) were charged to a heavy-walled glass tube. The tube was sealed andthen maintained at 150 C. for 18 hours. The catalyst was removed byfiltration after cooling. Vapor phase chromatography revealed that thefiltrate contained weight percent 1,5-cyclooctadiene and 50 weightpercent 1,3-cyclooctadiene.

EXAMPLE 12 Nickelocene (1.6 grams) and 4-methylcyclohexene (32 grams)were charged to a heavy-Walled glass tube. The tube was then sealed andmaintained at 185l92 C. for eighteen hours. Flash distillation of theresulting reaction product mixture gave 22 grams of distillate. This waschromatographed at 110 C. on a 100-foot capillary column coated withApiezon L. The chromatogram exhibited the presence of two components;one with a retention time of 3.6- minutes (59 weight percent of themixture), and the other with a retention time of 3.9 minutes (41 weightpercent of the mixture). Under these same conditions,4-methylcyclohexene has a retention time of 3.6 minutes andl-methylcyclohexene has a retention time of 3.9 minutes.

EXAMPLE l3 Cobaltocene (1.6 grams) and 4-methylcyclohexene (32 grams)were charged to a heavy-walled glass tube. The tube was sealed and thenmaintained at 180 C. for 18 hours. Flash distillation of the resultingreaction product mixture gave 24 grams of distillate. This waschromatographed at 110 C. on a 100-foot capillary column coated withApiezon L. The chromatogram exhibited the presence of two components;one with a retention time of 3.6 minutes (83-4 weight percent of themixture) and one with a retention time of 3.9 minutes (16.7 weightpercent of the mixture), e.g., l-methylcyclohexene.

EXAMPLE 14 A heavy walled glass tube was charged with 4 grams of4-methylcyclohexene and 0.2 gram of PdCl -2CN. The tube was then sealed,heated to 150 C. and maintained thereat for five hours. The resultingreaction product mixture was chromatographed at 110 C. on a 100- footcapillary column coated with Apiezon L. The

47A low vapor pressure grease which is useful in high vacuum work.

chromatogram exhibited the presence of two components; one with aretention time of 3.6 minutes and one with a retention time of 3.9minutes, e.g., l-methylcyclohexene.

EXAMPLE 15 A heavy walled glass tube was charged with 32 grams ofvinylcyclohexane and 1.6 grams of PdCl -2CN. The tube was then sealed,heated to 180 C. and maintained at that temperature for 18 hours.Analysis of the resulting reaction product mixture indicated that over70 weight percent of the vinylcyclohexane had been isomerized. Theisomerized products still contained one double bond, but the vinyl groupwas no longer present in these isomerized products.

EXAMPLE 16 A heavy walled glass tube was charged with 4 grams of1,5-cyclooctadiene and 0.2 gram of molybdenum hexacarbonyl. The tube wasthen sealed, heated to 250 C. and maintained at that temperature for 18hours. Analysis of the resulting reaction product mixture by vapor phasechromatography revealed the presence of 52 weight percent1,3-cyclooctadiene.

EXAMPLE 17 A heavy walled glass tube was charged with 4 grams of1,5-cyclooctadiene and 0.2 gram of 1r-allyl palladium (II) chloride. Thetube was then sealed, heated to C., and maintained at that temperaturefor 3 hours. Analysis of the resulting reaction product mixture by vaporphase chromatography revealed it to be essentially pure1,3-cyclooctadiene.

EXAMPLE 18 A heavy walled glass tube was charged with 4 grams of1,5-cycl0octadiene and 0.2 gram of tungsten hexacarbonyl. The tube wasthen sealed, heated to 185 C., and maintained at that temperature for 18hours. Analysis of the product by vapor phase chromatography revealedthe presence of 1,3-, 1,4-, and 1,5-cyclooctadienes.

EXAMPLE 19 A heavy walled glass tube was charged with 2 grams ofcyclopentadienyl manganese butadiene carbonyl 20 ml. of n-heptane, and20 ml. of butadiene. After sealing the tube, the solution was heated at140 C. for 5 hours. The tube and contents were cooled to Dry Icetemperature and the tube opened. The contents were filtered to remove asmall amount of precipitate. The filtrate was flash distilled at reducedpressure. The distillate was analyzed by vapor phase chromatography andfound to contain, in addition to unreacted butadiene and solvent, about60 weight percent of rearranged products of 4-vinylcyclohexene.

EXAMPLE 20 To 2,560 grams of refluxing 1,5-cyclooctadiene, there wasadded 12.8 grams of PdCl -2 P. The resulting solution was refluxed undera nitrogen atmosphere for two hours. Analysis of the resulting reactionproduct mixture by vapor phase chromotography revealed the presence of3.3 percent 13-, 73.7 percent 1,4- and 23.0 percent 1,5- cyclooctadiene.

EXAMPLE 21 A heavy walled glass tube was charged with 4 grams of1,5-cycl0octadiene and 0.2 gram of 1,5-cyclooctadiene platinum (II)chloride. The tube was then sealed, heated to C. and maintained at thattemperature for 18 hours. Analysis of the resulting reaction productmixture by vapor phase chromatography revealed the presence of 18percent 1,3-cyclooctadiene, 11 percent 1,4-cyclooctadiene and 71 percent1,5-cycl0octadiene.

9 EXAMPLE 22 A heavy walled glass tube was charged with 4 grams of1,5-cyclooctadiene and 0.2 gram of a ruthenium complex of1,5-cyclooctadiene. The tube was then sealed, heated to 180 C. andmaintained at that temperature for 18 hours. Analysis of the resultingreaction product mixture by vapor phase chromatography revealed 92percent 1,3-cyclooctadiene present therein.

EXAMPLE 23 A heavy walled glass tube was charged with 4 grams of1,5-cyclooctadiene and 0.2 gram of rhodium-containing complex. The tubewas then sealed, heated to 180 C. and maintained at that temperature for18 hours. Analysis of the resulting reaction product mixture by vaporphase chromatography revealed the presence of 17.4 percent1,3-cyclooctadiene, 37.1 percent 1,4-cyclooctadiene, and 45.5 percent1,5-cyclooctadiene.

EXAMPLE 24 To a flask equipped with a magnetic stirrer, there is added40 grams of thc' olefinic compound vinylcyclohexane and 2.0 grams ofPdCl -2CN. The contents of the flask are maintained at about 40 C.overnight. During this time appreciable amounts of C=C are shifted fromthe vinyl terminal position into the ring of the olefinic compound.

It is not intended that the above acts to limit the claims herein exceptto the extent provided by the claims.

What is claimed is:

1. An isomerization process which comprises contacting an ethylenicallyunsaturated compound at an elevated temperature in the presence of acatalytic amount of .a transition metal catalyst and for a period oftime sufiicient to produce a shift in the position of the double bond ofsaid ethylenically unsaturated compound; said compound being composed ofhydrogen and carbon, a cycloaliphatic nucleus having up to 16 carbonatoms in said nucleus and at least one migratable ethylenic bond; saidtransition metal catalyst comprising a transition metal in one of itsoxidation states capable of forming d.'sp. hybrid orbitals, saidtransition metal being furnished by a transition metal compound capableof forming a homogeneous phase with said ethylenically unsaturatedcompound and as such the transition metal compound represents saidtransition metal catalyst, and separating the resulting isomer.

2. A process which comprises contacting an ethylenically unsaturatedcompound, said compound being composed of hydrogen and carbon, acycloaliphatic nucleus having up to 16 carbon atoms in said nucleus, andat least one isomerizable ethylenic bond; with a catalytic amount of atransition metal in one of its oxidation states capable of forming d.sp.hybrid orbitals, said transition metal being furnished by a transitionmetal compound capable of forming a homogeneous phase with saidethylenically unsaturated compound; at an elevated temperature and for aperiod of time sufiicient to produce a shift in the position of thedouble bond of said ethylenically unsaturated compound, and separatingthe resulting isomer.

The ruthenium complex of 1,5-cyc10octadieue was prepared as follows: Asolution of ruthenium tricltlo-ride (1 gram), 40 ml. of ethanol (100%)and 5 ml, of 1,5-cyclooctadiene was heated at 79 C. for 4.5 hours undera nitrogen atmosphere. Cooling toroom temperature did not produce anysolid. The solvent was removed in vacuum and the dark residue trituratedwith methyl cycl'ohexane. Filtration gave 980 milligrams of shiney blackpowder. Ananlysis.Found: g, (2,1504% H, 3.93%; Ash, 40.94 (Ru, 31137:.if ash is The rhodium containing complex was prepared in the followingmanncr Bis (cycloocta 1,5 diene) -,u,u-dichlororhodium(I) (25millimoles, 1.23 grams) was dissolved in 60 m1. CH2CI2. The addition of0.55 gram of benzonitrile did not produce any precipitate. The solventwas removed in a nitrogen stream. The residue was triturated withcyclohexane. The solid portion of the product was washed well withcyclohexane and dried under vacuum (1 mm of Hg) for 3 hours;

yield 1.025 grams; M.P. 215-222 ((1.). Analysis-Found: C, 39.07, 38.75%H, 4.98, 4.82% N, 6.10% Rh, 43.90%.

3'. A process which comprises contacting an isomerizable ethylenicallyunsaturated hydrocarbon selected from the group consisting of (a)cycloolefins having from 2 to 3 ethylenic bonds, (b) alkyl substitutedcycloolefins having from 1 to 3 ethylenic bonds, (c) vinyl substitutedcycloolefins having from 1 to 3 endocyclicethylenic bonds, and (d) vinylsubstituted cycloalkanes, said ethylenically unsaturated hydrocarbonscontaining not more than 16 carbon atoms in the cycloaliphatic nucleusthereof; with a catalytic amount of a transition metal in one of itsoxidation states capable of forming d.sp. hybrid orbitals, saidtransition metal being furnished by a transition metal compound capableof forming a homogeneous phase with said ethylenically unsaturatedhydrocarbon; at an elevated temperature; and for a period of timesufficient to produce a shift in the position of the double bond of saidisomeriza'ble ethylenically unsaturated compound, and separating theresulting isomer.

4. The process of claim 3 wherein said transition metal is a Group VIIImetal.

5. The process of claim 3 wherein said transition metal is a Group VIIBmetal.

6. The process of claim 3 wherein said transition metal is a Group VIBmetal.

7. The process of claim 3 wherein said transition metal is a Group VBmetal.

8. The process of claim 3 wherein said transition metal is a Group IVBmetal.

9. The process of claim 3 wherein said transition metal is iron.

10. The process of claim metal is cobalt.

3 wherein said transition 11. The process of claim 3 wherein saidtransition metal is nickel.

12. The process of claim 3 wherein said transition metal is ruthenium.

13. The process of claim 3 wherein said transition metal is rhodium.

14. The process of claim 3 wherein said transition metal is palladium.

15. The process of claim 3 wherein said transition metal is iridium.

16. The process of claim 3 wherein said transition metal is osmium.

17. The process of claim 3 wherein said transition metal is platinum.

18. -A process which comprises contacting an isomerizablecyclodiolefinic hydrocarbon having up to 12 carbon atoms in thecycloaliphatic nucleus, with from about 0.005 to about 8 weight percent,based on the weight of said hydrocarbon, of a Group VIII transitionmetal in an oxidation state capable of forming d.sp. hybrid orbitals,said transition metal being furnished by a trans1tion metal compoundcapable of forming a homogeneous phase with said hydrocarbon; at atemperature in the range of from about 25 C. to about 225 C.; and for aperiod of time sufiicient to produce a shift in the position of thedouble bond of said hydrocarbon, and separating the resulting isomer.

19. A process which comprises contacting an isomerizable alkylsubstituted cyclomonoolefinic hydrocarbon having up to 12 carbon atomsin the cycloaliphatic nucleus, with from about 0.005 to about 8 weightpercent, based on the weight of said hydrocarbon, of a Group VIIItransition metal in an oxidation state capable of forming d.sp. hybridorbitals, said transition metal being furnished by a transition metalcompound capable of forming a homogeneous phase with said hydrocarbon;at a temperature in the range of from about 25 C. to about 225 C.; andfora period of time sufficient to produce a shift in the position of thedouble bond of said hydrocarbon, and separating the resulting isomer.

20. A process which comprises contacting an isomerizable alkylsubstituted cyclodiolefin'ic hydrocarbon having up to 12 carbon atoms inthe cycloaliphatic nucleus, with from about 0.005 to about 8 Weightpercent, based on the Weight of said hydrocarbon, of a Group VIIItransition metal in an oxidation state capable of forming d.sp. hybridorbitals, said transition metal being furnished by a transition metalcompound capable of forming a homogeneous phase With said hydrocarbon;at a temperature in the range of from about 25 C. to about 225 C.; andfor a period of time sufficient to produce a shift in the position ofthe double bond of said hydrocarbon, and separating the resultingisomer.

21. A process which comprises contacting an isomerizable vinylsubstituted cyclomonoolefinic hydrocarbon having up to 12 carbon atomsin the cycloaiiphatic nucleus, with from about 0.005 to about 8 Weightpercent, based on the weight of said hydrocarbon, of a Group VIIItransition metal in an oxidation state capable of forming d.sp. hybridorbitals, said transition metal being furnished by a transition metalcompound capable of forming a homogeneous phase with said hydrocarbon;at a temperature in the range of from about'25" C. to about 225 C.; andfor a period of time sufficient to produce a shift in the position ofthe double bond of "dro'carbon, of a Group VIII transition metal in anoxiidation state capable of forming d.sp. hybrid orbitals, said metalbeing furnished by a transition metal compound capable of forming ahomogeneous phase with said vinylcycloalkaneyat a temperature in therange of from about 25 C..to about 225 C.; and for a period of timesufficient to produce a shift in the position of the double bond of saidvinylcycloalkane, and separating the resulting isomer. 7 v I 23. Aprocess for the preparation of cyclooctadiene- 1,3 comprising heatingcycloocta'diene-LS at an isomer'izing temperature Wit-h a catalyticamount'of a palladium chloride catalyst, and separatingcyclooctadiehe-LB from the resulting reaction mixture.

No references cited.

DELBERT E. GAN l'Z, Primary Examiner.

V. OKEEFE, Assistant Examiner.

